Process of manufacturing steel



UNITED STATES PATENT. OFFICE.

ROBERT H. IRONS, OF HARRISBURG, PENNSYLVANIA, ASSIGNOR T0 CENTRAL IRON 8a STEEL COMPANY, OF HARRISBURG, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA.

PROCESS OF MANUFACTURING STEEL.

No Drawing.

T 0 all whom it may concern Be it known that 1, Roman H. Irons, a citizen of the United States, residing in Harrisburg, Dauphin county, Pennsylvania, have invented certain Improvements in Processes of Manufacturing Steel, of which the following is a specification.

My invention relates to an improvement in the art of making steel wholly, or largely, from steel scrap in a basic open hearth furnace, when a carbonaceous material is used to supply carbon to melt the heat of steel.

In making steel, according to this method, the carbonaceous material employed generally contains sulfur in quantities ranging from 0.5 to 1.5%, with the result that considerable difficulty is experienced in male ing steel sufiiciently low in sulfur. As a result, when low sulfur steel is required, ad ditional time is necessary for working the sulfur down to the required point so that not only is the time of the heat lengthened but the output of the furnace is'also lessened.

One object of my invention, therefore, is to provide a method utilizing the above de; scribed. scrap anl carbon process, which shall not involve the necessity of working out the sulfur at the end of the heat.

Another object of the invention is to provide a process of the above class whereby it shall be possible to produce a relatively hi her grade steel than can be obtained by the methods now employed ;-the invention contemplating a succession of steps whereby the oxidation of iron, or the absorption of iron oxid bythe steel in the bath, is prevented, with the result that the surfaces of the ingots produced by my process, and the productsW-olled from said ingots, are relatively free from imperfection.

I have (liscov'ermlthat in carrying out the scrap and carbon process of manufacturing steel, a large part of the sulfur in the heat may beelin'iinated by adding to the charge a material having a high manganese ontent in such amounts that. during the whole of the refining process in the basic open hearth furnace there is residual manganese in the steel and the slagis saturated with oxid of manganese. The saturation point of the slag is reached with an oxid of man anesc content offrom 6% to 9%. The high manganese. content of the charge is best man anese, a hi her rade steel Specification of Letters Patent. Patented June 29, 1920 Application filed August 14, 1919. -Serial No. 317,520.

secured by adding manganese ore thereto, but it may also be obtained by adding man ganese alloys to the charge or to the bath when the charge is melted.

Under conditions of operation, if manganese ore be used all or part of the oxid of manganese in the ore is reduced by the coke or carbonaceous material. Under these conditions, the reduced manganese is alloyed with the steel, thus giving the desired residual manganese in the bath, while any un-- reduced manganese orepasses into the slag. If, for any reason, there is not sui'licient oxi d of manganese in the slag to bring it to the point of saturation, the steel will lose part of its residual manganese by oxidation and the transfer of oxid to the slag. Such loss, however, may be kept at a minimum by increasing the capacity of the slag in lime and oXid of iron, which, combined with the oxid of manganese acting as a base, exerts the desired effect on the manganese of the bath.

As the working of the charge progresses, its temperature rises, until, finally, by reason of the high lime and, particularly, the high oxid of manganese content of the slag, the carbon is eliminated more rapidly than the manganese and the residual manganese can beheld at from 0.15% to 0.30% at the end of the heat. lnder the above conditions, the sulfur in the steel combines with part of the residual manganese in prefer once to the iron so that sullid (if-manganese is formed, which being insoluble in the molten steel, passes off into the slag. In other words the slag is saturated with manganese and the excess of this element present combines with the sulfur to form manganese sulfid which passes into the slag where it is retained.

-in carrying out the scrap and carbon process, as above described with a residual is produced than can be obtained without such manga nese in the bath during the whole refining operation, since any oxidation of the iron in the bath is prevented by this residual manganese. As a result of such prevention of oxidation. and the consequent absorption of iron oxid by the steel of the bath, the surfaces of the ingots produced by my process and of the products rolled from such ingots are relatively free from imperfections.

-or largely, of steel scrap,

In a typical case a charge would consist of eighty tons of steel scrap, four tons of carbonaceous material, such as coke, and one and a half tons of oxid of manganese in the form of manganese ore, such as manganese oXid. Such a charge when melted in a basic open hearth furnace, with fourteen thousand. pounds of burned lime, provides a bath which is worked until the sulfur content has been brought down to the desired point, such as (1.05%, and the residual manganese is from 0.15% to 0.30%.

I claim:

1. The method of making a low sulfur steel which comprises the charging of a basic open hearth furnace with a charge made up wholly, or largely, of steel scrap, a carbonaceous material and. manganesecontaining material, the latter being in proportion to effect the removal of the sulfur as described; melting said charge and working the bath until the sulfur has been reduced to the desired point.

2. The method of making a low sulfur steel which consists in charging a basic open hearth furnace with a charge consisting of steel scrap, a carbonaceous material and a n1anganese-containing material the latter being in proportion to provide residual manganese in the bath during the entire refining process and maintain the slag sub stantially saturated with oxid of manganese.

3. The method of making steel which consists in preparing a charge made up wholly, a carbonaceous material and manganesecontaining material in proportion to provide residual mangafnese in the bath throughout the entire refining process; melting said charge in abasic open hearth furnace; and keeping the loss of the residual manganese at a minimum by increasing the basicity of the slag.

4. The method of making steel which conin preparing a charge made up wholly, or largely, of steel scrap, carboneous material, and a manganese-containing material in proportioi'i to provide residual manganese in the bath throughout the entire refining process; melting said charge in a basic open hearth furnace; and keeping the loss of the residual manganese at a mini mum by increasing the basicity of the slag in lime.

5. The method of carrying out the scrap and carbon process of manufacturing steel which consists in preparing a charge con sisting of scrap steel, carbonaceous material, and manganese-containing material in the approximate ratio of eighty tons scrap steel, four tons of carbonaceous material, and one and a half tons of manganese-containing material; melting said charge in a basic open hearth furnace; and working the charge to bring the sulfur content to a predetermined point while retaining the residual manganese. i I

6. The step in the method of carrying out" the scrap and'carbon process of manufacturing steel, which consists in supplying manganese-containing material to a charge of scrap steel and carbonaceous material in a basic open hearth furnace in such quantity as to throughout the refining operation.

In testimony whereof I have hereunto set my hand this 12th of August, A. D. 1919.

ROBERT H. IRONS.

provide residual manganese 

